This project continues a multifaceted examination of the nature, levels and human impact of exposures to airborne allergens. We will employ selective media and culture conditions to study bacteria actinomycetes and nutritionally fastidious fungi - especially those associated with stored biological materials and mist sources. Microbial floras of humidifiers will be carefully analyzed and exposure risks associated with indoor plant growth evaluated. In addition, selected basidiospores, ascospores and deuteromycete spores will be propagated, extracted and examined for biological activity using skin and provocative tests as well as immunosorbant (RAST) assays. Allergenic similarities among related taxa will be weighed using RAST neutralization and this technique will be used to compare allergenic activities of fungus extracts derived from various preparatory procedures. An assay for amorphous arthropod materials in domestic dusts also will be developed using RAST neutralization. Determinants of particle penetration into cars will be studied and effects of auto air conditioners on exposure of occupants assessed. Efforts to evaluate possible carriage of pollen allergens in aerosol fractions smaller than intact grains will be pursued using differential filtration of high volume samples. Finally, the potential value of multispectral microscopy for atmospheric particle analysis will be explored with special attention to identification of materials lacking typical morphology by light microscopy.